1. Field of the Invention
The present invention relates generally to data communication devices, and in particular, to a power shut-off and recovery circuit for use with data communication devices.
2. Background Art
Computer networks facilitate communication between individuals, businesses, and other entities. Computer networks include communication devices that support the communication of data from a sender to a receiver or data terminal. These communication devices include hubs that join communications lines together in a star configuration, routers that make decisions about which of several paths network traffic (in the form of data packets) will follow, repeaters that copy electrical signals from one Ethernet to another to extend the transmission distance, and bridges that connect two or more networks and forward packets among them.
FIG. 1 illustrates a conventional network system which includes a communication device, which can be a hub, a repeater, a router or a bridge. The communication device has a plurality of ports PORT0, PORT1, PORT2 . . . PORTN through which communication lines can be connected to a corresponding number of data terminals DT0, DT1, DT2 . . . DTN.
One disadvantage with conventional communication devices is that they are powered twenty-four hours-a-day even though the network is actually in use for only a specific number of hours during the day. In other words, since a communication device is only used when two or more users (i.e., data terminals) communicate via the communication device, the communication device is typically not used except during office hours. Unfortunately, these communication devices do not have any shut-off and recovery mechanism. This leads to two drawbacks. First, by keeping these communication devices on and powered continuously, the maintenance costs (e.g., electricity costs) for these devices increase, and power and energy are unnecessarily wasted. Second, by continuously powering these devices twenty-four hours-a-day, seven days a week, the electronic parts in these devices experience a shorter life than parts in a device that is powered only periodically. In other words, continuous and prolonged operation makes these communication devices more susceptible to damage from over-heating, wear, and device failure.
Thus, there still remains a need for a power shut-off and recovery mechanism for data communication devices so that unnecessary power consumption is curbed, and the life of the communication device is lengthened.
It is one object of the present invention to provide a power shut-off and recovery circuit that turns off a communication device when a first predetermined condition is met.
It is another object of the present invention to provide a power shut-off and recovery circuit that turns on a communication device when a second predetermined condition is met.
It is a further object of the present invention to provide a power shut-off and recovery circuit that reduces wasteful and unnecessary power consumption by a communication device.
It is yet another object of the present invention to provide a power shut-off and recovery circuit that increases the life of a communication device.
It is yet a further object of the present invention to provide a power shut-off and recovery circuit that does not impact the quality of the communication signals between the communication device and the data terminals.
To accomplish the objectives set forth above, the present invention provides a data communication network having a first communication device that includes a plurality of ports, and a control coupled to the ports and having a plurality of outputs extending from the control, with each of the outputs indicative of the status of one of the ports. The network further includes a power shut-off and recovery circuit coupled to the first communication device, and having a first signal detection circuit coupled to the ports for detecting activity on each port and for generating a first signal indicative of the activity, and a second signal detection circuit coupled to the outputs for detecting activity on each port and for generating a second signal indicative of the activity. The power shut-off and recovery circuit further includes a power control circuit that is coupled to the first and second signal detection circuits for receiving the first and second signals, respectively, and for selectively asserting an ENABLE signal based on either the first signal or the second signal. A source transfer circuit is coupled to receive the ENABLE signal for selectively disengaging a power source from the communication device based on the ENABLE signal.
In operation, the network detects the presence of a communication signal from each of the plurality of ports via the plurality of outputs and the second signal detection circuit, and determines the number of signals received from the outputs. The power supply to the communication device is disengaged if the number of signals received from the outputs is smaller than a predetermined number. Thereafter, the network detects the presence of a communication signal from each of the ports via the first signal detection circuit, and determines the number of signals received from the ports. The power supply to the communication device is reconnected if the number of signals received from the ports is greater than a predetermined number. Thus, when the second signal detection circuit is used to provide the outputs to the power control circuit to indicate the status of the ports, the first signal detection circuit can be turned off, so that the communication signals at the ports are not sampled by the first signal detection circuit. This ensures that the quality of the communication signals will not be compromised by the operation of the power shut-off and recovery circuit.